The present invention generally relates to magnetic tape reproducing apparatuses, and more particularly to a magnetic tape reproducing apparatus of the helical scan type.
In a helical scan type magnetic tape reproducing apparatus, a magnetic tape having video tracks formed obliquely to the longitudinal direction thereof is wrapped spirally and guided around an outer peripheral surface of a tape guide drum. Rotary video heads mounted on the guide drum scan obliquely to the longitudinal direction of the magnetic tape so as to scan over the video tracks and reproduce recorded video signals from the video tracks. In a normal reproducing mode in which the magnetic tape moves in a direction (forward direction) at a speed essentially identical to the tape moving direction (forward direction) and tape moving speed at the time of the recording, scanning loci of the rotary video heads coincide with the video tracks on the magnetic tape. However, in a special reproduction mode in which the tape moving direction and/or the tape moving speed is different from the tape moving speed and/or the tape moving direction at the time of the recording, the scanning loci of the rotary video heads do not coincide with the video tracks on the magnetic tape. In the special reproduction mode, each scanning loci of the rotary video heads traverses a plurality of video tracks, and as a result, noise is inevitably generated in a reproduced picture.
In order to suppress the generation of noise during the special reproduction mode, there is a conventional reproducing apparatus in which the rotary video heads are supported on piezoelectric elements. The piezoelectric elements are bent (deformed) by applying an external voltage to the piezoelectric elements, so that the rotary video heads scan along the video tracks on the magnetic tape. However, due to the limitation introduced by the response speed and the bending quantity of the piezoelectric elements, the rotary video heads cannot follow the video tracks when the tape moving speed in the special reproduction mode becomes greater than approximately three times the tape moving speed of the normal reproduction mode. Therefore, when the tape moving speed in the special reproduction mode is high, each of the rotary video heads traverse a plurality of tracks and noise is generated in the reproduced picture. In other words, the conventional reproducing apparatus has a disadvantage in that the range of the tape moving speed in the special reproduction mode that will not generate noise, is limited to a relatively small range. In addition, the piezoelectric elements of the conventional reproducing apparatus requires a complex control. Thus, there are disadvantages in that a control system for controlling the piezoelectric elements of the conventional reproducing apparatus is complex and expensive.